What Causes Itchy Vaginal Lips During 28 Weeks Of Pregnancy?

I am currently 28 weeks pregnant and have been experiencing an itch on the inside lip of my vagina.. i haven't had sex nor does it burn while i pee. im concerned about what it could be. i looked in the mirror and it was a little red "patch" at the top right of my right lip it itches really bad& makes me uncomfortable. any opinions or suggestions?